Thread: 15 inch Overhead beam

First, make a drilling jig - just get a small piece of heay timber, say 100 x 50 x 300 mm - and dril a hole in the middle with a drill press. his ensures it is vertical.

Second, clamp the jig in position underneath the ceiling beam.

Third, drill the hole using the jig as your aligning tool,

Fourth. The drill bit must be of the needed diameter and at least 15 inches cutting length. Personally, I would prefer a spurred auger bit like this as they drill cleanly and accurately.

Spurred Auger Bit.jpg

I would avoid standard twist drill bits or spade bits as, in my hands, they do not drill accurately over those distances.

How thick is the beam? Make sure you're not taking out too much meat of the beam?


I'd suggest similar to the method above, but starting with a smaller length bit. So pretty much a standard drill bit and an nice accurate guide to start off.

Then look at a guide/jig for your long boy 400mm bit.

At least with the hole started theres less chance of it wandering off

Running the wire down the outside of the beam isn’t an option?

Hi,

In reply the beam is 8cm/ 3 1/4 inches thick.

Hi,

In reply, no I don't want to run the wires down the side of the beam as its a feature stained beam that runs the length of the room. I want to hide the wires. Beam is 38 cm in height and 8 cm thick.

Originally Posted by havabeer69

I'd suggest similar to the method above, but starting with a smaller length bit. So pretty much a standard drill bit and an nice accurate guide to start off.

A thin bit 400 mm long would be very fragile and flexible - likely to wander all over the place, until it breaks.

That is why I recommended a spurred bit that could do it in a single pass. Hole for a single wire will only need to be 8 mm or so.

Originally Posted by GraemeCook

First, make a drilling jig

Spurred Auger Bit.jpg

A jig as described is worth the effort. If you buy a bit like this it will want to pull itself through the timber faster than you'll expect. Consider a hand brace or setting your machine to a slow speed.

I would use the drilling jig Graeme mentioned but start the hole with a shorter standard drill bit to get a 2 to 3 inch start on the hole. Then your longer auger will be set to mostly go through OK.
With augers and the small screw at its tip . I have filed these a bit dull sometimes to slow the aggressive pull they have into the wood. The more you dull them the more you have to push though. That's better than losing control though.

Rob

Originally Posted by GraemeCook

A thin bit 400 mm long would be very fragile and flexible - likely to wander all over the place, until it breaks.

That is why I recommended a spurred bit that could do it in a single pass. Hole for a single wire will only need to be 8 mm or so.

Indeed! I had a 300mm 5mm Scotch pattern bit, I called the wonder bit, you'd always wonder where it was going to come out!

Perfectly straight or perfectly plumb and why is either important just to feed wires?

Originally Posted by rustynail

Perfectly straight or perfectly plumb and why is either important just to feed wires?

I would assume its an exposed beam... and it might like a bit silly if 3/4 up the side of the beam a random hole and wire juts out that then has to be fed into the roof




like the fan in this picture, but without a wire on either side

ceiling-fan-hung-on-beam-should-we-drill-a-hole-through-v0-yo6h78jigs0b1.jpg

It would need to be an extraordinarily inaccurately drilled hole to pop out the side ¾ of the way up!

I think Forum members have pretty much nailed it. While the beam is sufficiently thick to allow for error in drilling, a guide to start (post #2)and a shorter drill initially (post #8) are going to make life easier. This is because you are drilling upwards. While auscabs comment on this type of drill with the threaded tip is correct and does tend to pull itself rapidly through timber if using a corded tool, I would not worry about filing the thread off. Just use a cordless drill, possibly on the slower speed to begin with, as this will be easily controllable. As you are drilling up any assistance from the screw tip will be welcomed. A drill bit of 12mm or 10mm would be ample for lighting wire.

Using a guide and a short drill first will mean not having to concentrate so hard on the task and you can just drill.

Regards
Paul

Dangle a plumb bob down the side of the beam as a reference to help keep the drill vertical. It's a good idea to have a second person as a "navigator" as you need to observe the string from two directions to be plumb.
Just a thought - Check that the beam is actually hanging plumb before you start drilling. If not, a batten clamped to the side of the beam would give the correct angle.